Objective: Antidepressants are recommended for the treatment of depressive and anxiety symptoms in patients with major depressive disorder, but caution is urged when used for the treatment of these symptoms in bipolar disorder. It is not known whether these differing recommendations are reflected in clinical practice, as comparative analyses of rates of antidepressant use between bipolar disorder and major depressive disorder subjects with or without comorbid anxiety have not been reported.
Method: Data source was the Canadian Community Health Survey on Mental Health and Well-Being, a large, representative mental health survey conducted from May to December 2002. Rates of antidepressant use were compared for subjects with bipolar disorder according to the World Mental Health-Composite International Diagnostic Interview or major depressive disorder according to DSM-IV criteria, with or without comorbid anxiety (DSM-IV). The independent effects of the diagnostic group and of a comorbid anxiety disorder were determined by controlling for sociodemographic and clinical variables using logistic regression.
Results: Rate of antidepressant use was significantly higher among all subjects with bipolar disorder (N = 756) compared with all subjects with major depressive disorder (N = 3863) (27.2% vs. 23.1%, p = .02), but this difference was no longer significant when other factors were controlled for in the regression analysis. With the major depressive disorder without anxiety group as the reference, the likelihood of antidepressant use was significantly higher in both the bipolar disorder with anxiety group (OR = 1.83, 95% CI = 1.02 to 3.27, p = .04) and the major depressive disorder with anxiety group (OR = 1.45, 95% CI = 1.00 to 2.09, p = .05).
Conclusion: After sociodemographic and clinical variables were controlled for, similar rates of antidepressant use were identified among bipolar disorder and major depressive disorder subjects. Further efforts are needed to enhance screening for bipolar disorder among depressed patients and to re-examine the risk/benefit analysis of antidepressants for bipolar disorder patients in light of emerging alternatives. Significantly increased rates of antidepressant use in subjects with a comorbid anxiety disorder suggest that anxiety symptoms may be a key reason why physicians are choosing to prescribe antidepressants for patients with bipolar disorder and major depressive disorder.